cleaning dirty speedometers (inside)

[MonaLS]

I've never posted on any forum so please bare with me. I have a 2011 CooperS Convertible. I have noticed recently that there is dust inside my speedometer and today after having it washed there was water droplets. I'd love to be able to pop the damn trim and plexiglass off and clean it myself but I'm sure that's not really a good idea. But if it's possible I'd love to hear from someone that has actually done it.
Also the Airbag warning light is now on....I'm not sure what that means. I've looked it up in the manual and the explanation didn't make sense to me.....it's an indication that its working or not!! I'm not very mechanical but I'm also not stupid....ha.
Help and thanks...m ; )

[The Nun]

How are you getting water droplets in the speedo? do you put the roof up when you wash the car?
If the cars letting in water due to it leaking theres a good chance the seat airbag connections under the seats are giving problems due to dampness hence the warning?

[AustinS]

I hope MonaLS means she got water inside when she washed the speedo face. Maybe she sprayed it with Windex.

My speedo is dirty inside also and I would love to know how to get the face off.